Tag: Milky Way

The total number of stars in the Universe “is likely three times bigger than realized.” Yale University astronomer Pieter van Dokkum says there are “possibly trillions of Earths orbiting these stars,” dramatically increasing the possibility of finding alien civilizations.

According to the new study just published in Nature, new observations on the red end of the optical spectrum at the W. M. Keck Observatory in Hawaii show an overwhelming population of red dwarfs in eight massive nearby elliptical galaxies. The team has discovered that these galaxies hold twenty times more red dwarfs than the Milky Way.

Van Dokkum says that “there are possibly trillions of Earths orbiting these stars” which are “typically more than 10 billion years old.” According to him, that’s long enough for complex life to evolve, which is “one reason why people are interested in this type of star.” In fact, astronomers discovered the first exoplanet similar to our own Earth—and therefore capable of harboring complex life—orbiting the Gliese 581 red dwarf star system, 20.3 light years from our home planet.

An image released by NASA Tuesday, shows Sagittarius A, the supermassive black hole at the center of the Milky Way Galaxy made from data provided by the Chandra X-ray Observatory. Credit: NASA/AP

One of the Milky Way’s longstanding puzzles centers on the super-massive black hole at its core, in the constellation Sagittarius: Why is that monstrous black hole, known as Sag A*, so much less energetic that its counterparts in other galaxies?

The behemoth, with some 2.6 million times the sun’s mass, is a cosmic dud at the moment. Something is starving it, depriving it of material that otherwise would plummet into it.

Roman Shcherbakov, a researcher at the Harvard-Smithsonian Center for Astrophysics, says he’s figured out what that “something” is likely to be: heat.

As material from surrounding stars approaches the black hole and gets compressed by the monster’s gravity, it heats up. Some of that heat gets conducted away from the black hole, setting up a source of pressure that sweeps material away from the voracious object.

In other words, heating around the black hole’s event horizon – essentially the boundary within which material falls into oblivion – is in effect starving the black hole.

Now speeding through space at more than 34,000 miles-per-hour, the 1977 space probe resides more than 8.3. billion miles away from the sun. That is twice as far as Pluto. Two years ago, Voyager 2 passed into the region of space where the sun’s solar wind peters out as it plows into the interstellar gases of our Milky Way galaxy. And now it’s giving us some news from this region, called the “heliosheath,” by astrophysicists.

“This is a magic mission,” says space scientist Merav Opher of George Mason University. in Fairfax, Va.. “After all these years, Voyager 2 is still working and sending us first hand (on-site) data.”